[libc] Add C23 limits.h header.

libc/cmake/modules/LLVMLibCLibraryRules.cmake

@@ -173,7 +173,17 @@ function(create_header_library fq_target_name)
   target_sources(${fq_target_name} INTERFACE ${ADD_HEADER_HDRS})
   if(ADD_HEADER_DEPENDS)
     add_dependencies(${fq_target_name} ${ADD_HEADER_DEPENDS})
-    target_link_libraries(${fq_target_name} INTERFACE ${ADD_HEADER_DEPENDS})
+
+    # `*.__copied_hdr__` is created only to copy the header files to the target
+    # location, not to be linked against.
+    set(link_lib "")
+    foreach(dep ${ADD_HEADER_DEPENDS})
+      if (NOT dep MATCHES "__copied_hdr__")
+        list(APPEND link_lib ${dep})
+      endif()
+    endforeach()
+
+    target_link_libraries(${fq_target_name} INTERFACE ${link_lib})
   endif()
   if(ADD_HEADER_COMPILE_OPTIONS)
     target_compile_options(${fq_target_name} INTERFACE ${ADD_HEADER_COMPILE_OPTIONS})

libc/config/darwin/arm/headers.txt

@@ -4,6 +4,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.fenv
     libc.include.float
     libc.include.inttypes
+    libc.include.limits
     libc.include.math
     libc.include.stdlib
     libc.include.string

libc/config/darwin/x86_64/headers.txt

@@ -5,6 +5,7 @@ set(TARGET_PUBLIC_HEADERS
     #libc.include.fenv
     libc.include.float
     libc.include.inttypes
+    libc.include.limits
     libc.include.math
     libc.include.stdlib
     libc.include.string

libc/config/gpu/headers.txt

@@ -4,6 +4,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.string
     libc.include.float
     libc.include.inttypes
+    libc.include.limits
     libc.include.math
     libc.include.fenv
     libc.include.time

libc/config/linux/aarch64/headers.txt

@@ -6,6 +6,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.fenv
     libc.include.float
     libc.include.inttypes
+    libc.include.limits
     libc.include.math
     libc.include.pthread
     libc.include.signal

libc/config/linux/riscv/headers.txt

@@ -8,6 +8,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.fenv
     libc.include.float
     libc.include.inttypes
+    libc.include.limits
     libc.include.math
     libc.include.pthread
     libc.include.sched

libc/config/linux/x86_64/headers.txt

@@ -8,6 +8,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.fenv
     libc.include.float
     libc.include.inttypes
+    libc.include.limits
     libc.include.math
     libc.include.pthread
     libc.include.sched

libc/include/CMakeLists.txt

@@ -83,6 +83,14 @@ add_gen_header(
     .llvm-libc-macros.float_macros
 )
 
+add_gen_header(
+  limits
+  DEF_FILE limits.h.def
+  GEN_HDR limits.h
+  DEPENDS
+    .llvm-libc-macros.limits_macros
+)
+
 add_gen_header(
   math
   DEF_FILE math.h.def

libc/include/limits.h.def

@@ -0,0 +1,14 @@
+//===-- C standard library header limits.h --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_LIMITS_H
+#define LLVM_LIBC_LIMITS_H
+
+#include <llvm-libc-macros/limits-macros.h>
+
+#endif // LLVM_LIBC_LIMITS_H

libc/include/llvm-libc-macros/CMakeLists.txt

@@ -73,6 +73,12 @@ add_macro_header(
     float-macros.h
 )
 
+add_macro_header(
+  limits_macros
+  HDR
+    limits-macros.h
+)
+
 add_macro_header(
   math_macros
   HDR

libc/include/llvm-libc-macros/float-macros.h

@@ -9,8 +9,20 @@
 #ifndef __LLVM_LIBC_MACROS_FLOAT_MACROS_H
 #define __LLVM_LIBC_MACROS_FLOAT_MACROS_H
 
+// Suppress `#include_next is a language extension` warnings.
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wgnu-include-next"
+#else // gcc
+#pragma GCC system_header
+#endif //__clang__
+
 #include_next <float.h>
 
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif //__clang__
+
 #ifndef FLT_RADIX
 #define FLT_RADIX __FLT_RADIX__
 #endif // FLT_RADIX

libc/include/llvm-libc-macros/limits-macros.h

@@ -0,0 +1,226 @@
+//===-- Definition of macros from limits.h --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __LLVM_LIBC_MACROS_LIMITS_MACROS_H
+#define __LLVM_LIBC_MACROS_LIMITS_MACROS_H
+
+// Define all C23 macro constants of limits.h
+
+#ifndef CHAR_BIT
+#ifdef __CHAR_BIT__
+#define CHAR_BIT __CHAR_BIT__
+#else
+#define CHAR_BIT 8
+#endif // __CHAR_BIT__
+#endif // CHAR_BIT
+
+// TODO: https://github.com/llvm/llvm-project/issues/79358
+//   Define MB_LEN_MAX if missing.
+//     clang: MB_LEN_MAX = 1 -
+// https://github.com/llvm/llvm-project/blob/main/clang/lib/Headers/limits.h#L64
+//     glibc: MB_LEN_MAX = 16 -
+// https://github.com/bminor/glibc/blob/master/include/limits.h#L32
+
+// *_WIDTH macros
+
+#ifndef CHAR_WIDTH
+#define CHAR_WIDTH CHAR_BIT
+#endif // CHAR_WIDTH
+
+#ifndef SCHAR_WIDTH
+#define SCHAR_WIDTH CHAR_BIT
+#endif // SCHAR_WIDTH
+
+#ifndef UCHAR_WIDTH
+#define UCHAR_WIDTH CHAR_BIT
+#endif // UCHAR_WIDTH
+
+#ifndef SHRT_WIDTH
+#ifdef __SHRT_WIDTH__
+#define SHRT_WIDTH __SHRT_WIDTH__
+#else
+#define SHRT_WIDTH 16
+#endif // __SHRT_WIDTH__
+#endif // SHRT_WIDTH
+
+#ifndef USHRT_WIDTH
+#define USHRT_WIDTH SHRT_WIDTH
+#endif // USHRT_WIDTH
+
+#ifndef INT_WIDTH
+#ifdef __INT_WIDTH__
+#define INT_WIDTH __INT_WIDTH__
+#else
+#define INT_WIDTH 32
+#endif // __INT_WIDTH__
+#endif // INT_WIDTH
+
+#ifndef UINT_WIDTH
+#define UINT_WIDTH INT_WIDTH
+#endif // UINT_WIDTH
+
+#ifndef LONG_WIDTH
+#ifdef __LONG_WIDTH__
+#define LONG_WIDTH __LONG_WIDTH__
+#elif defined(__WORDSIZE)
+#define LONG_WIDTH __WORDSIZE
+#else
+#error "Unknown WORDSIZE to define LONG_WIDTH."
+#endif // __LONG_WIDTH__
+#endif // LONG_WIDTH
+
+#ifndef ULONG_WIDTH
+#define ULONG_WIDTH LONG_WIDTH
+#endif // ULONG_WIDTH
+
+#ifndef LLONG_WIDTH
+#ifdef __LLONG_WIDTH__
+#define LLONG_WIDTH __LLONG_WIDTH__
+#else
+#define LLONG_WIDTH 64
+#endif // __LLONG_WIDTH__
+#endif // LLONG_WIDTH
+
+#ifndef ULLONG_WIDTH
+#define ULLONG_WIDTH LLONG_WIDTH
+#endif // ULLONG_WIDTH
+
+#ifndef BOOL_WIDTH
+#ifdef __BOOL_WIDTH__
+#define BOOL_WIDTH __BOOL_WIDTH__
+#else
+#define BOOL_WIDTH 1
+#endif // __BOOL_WIDTH__
+#endif // BOOL_WIDTH
+
+// *_MAX macros
+
+#ifndef SCHAR_MAX
+#ifdef __SCHAR_MAX__
+#define SCHAR_MAX __SCHAR_MAX__
+#else
+#define SCHAR_MAX 0x7f
+#endif // __SCHAR_MAX__
+#endif // SCHAR_MAX
+
+#ifndef UCHAR_MAX
+#define UCHAR_MAX (SCHAR_MAX * 2 + 1)
+#endif // UCHAR_MAX
+
+// Check if char is unsigned.
+#if !defined(__CHAR_UNSIGNED__) && ('\xff' > 0)
+#define __CHAR_UNSIGNED__
+#endif
+
+#ifndef CHAR_MAX
+#ifdef __CHAR_UNSIGNED__
+#define CHAR_MAX UCHAR_MAX
+#else
+#define CHAR_MAX SCHAR_MAX
+#endif // __CHAR_UNSIGNED__
+#endif // CHAR_MAX
+
+#ifndef SHRT_MAX
+#ifdef __SHRT_MAX__
+#define SHRT_MAX __SHRT_MAX__
+#else
+#define SHRT_MAX 0x7fff
+#endif // __SHRT_MAX__
+#endif // SHRT_MAX
+
+#ifndef USHRT_MAX
+#define USHRT_MAX (SHRT_MAX * 2U + 1U)
+#endif // USHRT_MAX
+
+#ifndef INT_MAX
+#ifdef __INT_MAX__
+#define INT_MAX __INT_MAX__
+#else
+#define INT_MAX (0 ^ (1 << (INT_WIDTH - 1)))
+#endif // __INT_MAX__
+#endif // INT_MAX
+
+#ifndef UINT_MAX
+#define UINT_MAX (~0U)
+#endif // UINT_MAX
+
+#ifndef LONG_MAX
+#ifdef __LONG_MAX__
+#define LONG_MAX __LONG_MAX__
+#else
+#define LONG_MAX (0L ^ (1L << (LONG_WIDTH - 1)))
+#endif // __LONG_MAX__
+#endif // LONG_MAX
+
+#ifndef ULONG_MAX
+#define ULONG_MAX (~0UL)
+#endif // ULONG_MAX
+
+#ifndef LLONG_MAX
+#ifdef __LONG_LONG_MAX__
+#define LLONG_MAX __LONG_LONG_MAX__
+#else
+#define LLONG_MAX (0LL ^ (1LL << (LLONG_WIDTH - 1)))
+#endif // __LONG_LONG_MAX__
+#endif // LLONG_MAX
+
+#ifndef ULLONG_MAX
+#define ULLONG_MAX (~0ULL)
+#endif // ULLONG_MAX
+
+// *_MIN macros
+
+#ifndef SCHAR_MIN
+#define SCHAR_MIN (-SCHAR_MAX - 1)
+#endif // SCHAR_MIN
+
+#ifndef UCHAR_MIN
+#define UCHAR_MIN 0
+#endif // UCHAR_MIN
+
+#ifndef CHAR_MIN
+#ifdef __CHAR_UNSIGNED__
+#define CHAR_MIN UCHAR_MIN
+#else
+#define CHAR_MIN SCHAR_MIN
+#endif // __CHAR_UNSIGNED__
+#endif // CHAR_MIN
+
+#ifndef SHRT_MIN
+#define SHRT_MIN (-SHRT_MAX - 1)
+#endif // SHRT_MIN
+
+#ifndef USHRT_MIN
+#define USHRT_MIN 0U
+#endif // USHRT_MIN
+
+#ifndef INT_MIN
+#define INT_MIN (-INT_MAX - 1)
+#endif // INT_MIN
+
+#ifndef UINT_MIN
+#define UINT_MIN 0U
+#endif // UINT_MIN
+
+#ifndef LONG_MIN
+#define LONG_MIN (-LONG_MAX - 1L)
+#endif // LONG_MIN
+
+#ifndef ULONG_MIN
+#define ULONG_MIN 0UL
+#endif // ULONG_MIN
+
+#ifndef LLONG_MIN
+#define LLONG_MIN (-LLONG_MAX - 1LL)
+#endif // LLONG_MIN
+
+#ifndef ULLONG_MIN
+#define ULLONG_MIN 0ULL
+#endif // ULLONG_MIN
+
+#endif // __LLVM_LIBC_MACROS_LIMITS_MACROS_H

libc/spec/stdc.td

@@ -856,6 +856,8 @@ def StdC : StandardSpec<"stdc"> {
       ]
   >;
 
+  HeaderSpec Limits = HeaderSpec<"limits.h">;
+
   NamedType SigAtomicT = NamedType<"sig_atomic_t">;
   HeaderSpec Signal = HeaderSpec<
       "signal.h",
@@ -1159,6 +1161,7 @@ def StdC : StandardSpec<"stdc"> {
     Errno,
     Fenv,
     Float,
+    Limits,
     Math,
     String,
     StdIO,

libc/src/__support/CMakeLists.txt

@@ -34,6 +34,7 @@ add_header_library(
   HDRS
     math_extras.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.CPP.type_traits
     libc.src.__support.macros.attributes
     libc.src.__support.macros.config

libc/src/__support/CPP/CMakeLists.txt

@@ -48,6 +48,7 @@ add_header_library(
     limits.h
   DEPENDS
     .type_traits
+    libc.include.llvm-libc-macros.limits_macros
 )
 
 add_header_library(